1. Field of the Invention
This invention relates to the modification of television signals to produce a displayed image wherein compression or expansion occurs along preselected axes. More particularly, the invention relates to electronic arrangements for providing an anamorphic conversion on television signals indicative of scenes anamorphically recorded on motion picture films to provide a virtually undistorted television image of true proportion.
2. Description of the Prior Art
In order to provide a panoramic effect from motion picture film having standard sized frames, an anamorphic optical lens is used to compress the recorded image along the horizontal axis. when the recorded image is projected on a screen, another compatible anamorphic lens expands the projected image horizontally to provide an illuminated motion picture screen in true proportion. The increased width of the illuminated motion picture screen provides the panoramic effect.
Because of the impact of television, it has become desirable to broadcast motion pictures for home viewing on television receivers. Since the ratio of height to width dimensions of television receiver displays do not correspond to that of commercial motion picture screens, only a portion of the motion picture image along its horizontal axis is required to provide a television display in true proportion. Accordingly an editing process is employed by using an anamorphic converter wherein the most subjectively pleasing portion of the motion picture image is selected for television transmission.
Conventional anamorphic converters utilize optical means to enlarge or expand photographically produced images in the horizontal direction. In addition to a slight nonlinearity in the expansion ratio produced by aberrations in the anamorphic lens, the optical system is moved by mechanical or electromechanical means and exhibits inertia and hysteresis which tend to reduce accuracy of the reaction speed and overall responsiveness of the control system. These drawbacks make subjectively unacceptable rapid panning or instantaneous "go to" modes of operation.
Another problem is that the image produced by the prior art systems show only the portion of the information present on the photographic film that corresponds to the television aspect ratio of 3 vertical units to 4 horizontal units. For real time processing and editing of motion pictures for television, it would be desirable to see all the information present on the photographic film and be readily able to identify the portion therein being selected for the television display.
It is an object of this invention to provide a television image from an anamorphic photographic image employing electronic means capable of high resolution and dimensional linearity.
A further object is to provide an electronic anamorphic converter whose operation is compatible with real time editing when desired but also compatible with preprogramming techniques.